Abstract
In order to investigate the slip behavior near an interface in high cycle fatigue, a tension-compression fatigue test is carried out using a two-phase (α/γ) stainless steel bicrystal, which consists of ferritic (Fe30Cr) and austenitic (Fe11Cr19Ni) single crystals. Since the yield stress of α-phase is much higher than that of γ-phase, the crystallographic slip takes place only in the γ-phase. Characteristic slip, which is not expected from the Schmid factors, appears in the γ-phase near the interface. The stress analysis by a finite element method(FEM) reveals that the resolved shear stress, τ_<rss>, of the specific slip systems near the interface increases due to the constraint of deformation at the boundary. The characteristic slip takes place where the magnitude of Trss exceeds the critical stress of 31 MPa. This agrees well with the critical resolved shear stress, τ_<crss>, in the γ-single crystal. In short, the slip near the interface is governed by the local shear stress in the high cycle fatigue. The analytical result and the experimental observation point out that the increase of τ_<rss> on the specific slip system is confined in a region near the interface on the surface.
